Flowable media, as defined by the present invention, are frequently and especially used in drive technology, for example as a lubricant and/or coolant or as a pressurizing medium in hydraulic systems to transfer energy from a pressurizing medium source to a load. Flowable media are located in pressure devices, such as pressure containers or pressure lines. Pressure containers in particular can fulfill the widest variety of tasks in such hydraulic systems. For example, they may be used for energy storage, the provision of a fluid reserve, the emergency actuation of loads, shock absorption and the like. In addition to knowledge of the physical operating parameters, such as pressure or flow rates in those pressure devices, the safe and proper operation of a hydraulic system requires information about the quality of the flowable media in the hydraulic system or information as well about the presence of flowable media in regions of those pressure devices or in regions of the hydraulic system, respectively.
DE 101 52 777 A1 describes an apparatus for determining the quality of a medium, in particular of a lubricant and/or coolant, having multiple sensors. The sensors emit an electrical output signal as a function of the respective sensor-specific input variable. One sensor is a temperature sensor, which emits an output signal that is essentially only dependent on the temperature of the medium and in particular, is essentially independent of the quality of the medium. An additional sensor emits an output signal that is dependent both on the quality of the medium and on the temperature of the medium. The sensors used are disposed on a common substrate that can be submerged in the respective medium that is to be tested. The apparatus formed in this way permits determining the quality-determining parameters of flowing media independent of the current temperature of said media.
DE 10 2009 010 775 A1 describes a pressure device in the form of a hydraulic accumulator for accommodating at least a partial volume of pressurized fluid, in particular a hydropneumatic accumulator. The hydraulic accumulator has a housing having at least one connection point for connecting the hydraulic accumulator to a hydraulic device. Data memory is a component of the hydraulic accumulator such that the data saved to the data memory can be read electronically by a reading and/or writing device disposed outside the hydraulic accumulator. The operating condition of the hydraulic accumulator can thereby be reliably determined and monitored, preferably can also be carried out in an automated manner, and can be controlled by a control device.
If a sensor device is only used to detect the presence of flowable media in pressure devices of hydraulic systems and/or the type of flowable medium present, these known sensor devices present costly and complex solutions for this application.
DE 35 00 098 A1 discloses a sensor device conforming to its genre for detecting flowable media, in particular in the form of fluids, which can be received in pressure devices such as pressure containers or pressure lines. The sensing device has at least one sensor element. That sensor element has an oscillation device, which is excited to produce oscillations under the influence of a magnetic field of a field generation device. The oscillation behavior of those oscillations changes upon the influx of the respective medium. That the change can be detected by a measuring device. The field generation device is formed by a magnetic device. The measuring device is formed by at least one electromagnetic solenoid. In addition to an electrical voltage in the solenoid, the magnetic flux of the electromagnetic solenoid is influenced by the oscillations of the sensor element when that sensor element is excited.
The known solution has a complicated design and is, therefore, expensive and difficult to produce.